Oral administration of Schisandra chinensis extract suppresses Dnmt1 expression in Kunming mice ovaries

Abstract

The plant Schisandra chinensis contains a phytoestrogens, a type of naturally occurring estrogens which have multiple functions in a number of biological processes. To investigate the correlation between phytoestrogens and epigenetic modification, especially the effect of phytoestrogens on DNA methylation, sexually healthy female mice were used as an animal model in the present study. Briefly, the total RNA and protein were isolated from the ovary of mice after 7-day oral administration of Schisandra chinensis extract (SCE), while distilled water was given to the animals in the control group. Real-time PCR, Western blotting, and enzyme activity assays were performed to examine the effect of the extract of S. chinensis on Dnmt1 transcription and activity. A promoter assay was further conducted in MCF cells (ER positive) to explore also the influence of SCE on Dnmt1 transcriptional activity. The results revealed that the mRNA and protein expression levels of mouse Dnmt1 were both significantly downregulated in the treated group. The transcription of Dnmt1 was suppressed by SCE and in the E2-added group also. Meanwhile the numbers of oocytes at different stages were increased in the treated group when compared by histological analyses with those in the control group. Taken together, the results indicated that, similarly to the action of estrogen, phytoestrogens affected Dnmt1 transcription in mammals, regulating the related gene expression and cell differentiation. The findings of our examination provided also basic data and understanding for the correlation between phytoestrogens and epigenetic modification.